By all accounts, the conversation that U.S. President Barack Obama and Russian President Vladimir Putin will have in New York is likely to be serious and substantive over issues like Syria and Ukraine.

And judging by the sharp disagreement over who actually requested the meeting, it may turn out to be unpleasant, as well.

The meeting, scheduled for September 28 on the sidelines of the UN General Assembly, will be the first formal meeting between the two presidents since before Russia’s unrecognized annexation of Crimea and the subsequent sanctions by the United States and the European Union.

White House officials on September 24 confirmed the meeting would take place and made clear that it was being held at Putin's request.

"I think it is fair for you to say that based on the repeated requests we've seen from the Russians, that they are quite interested in having a conversation with President Obama," spokesman Josh Earnest told reporters during the daily press briefing.

Later, he appeared to joke that the Russians might have been "desperate" for the meeting.

White House national security adviser Ben Rhodes said European allies had urged Obama to meet with Putin to discuss how the Minsk agreements, to end the conflict in Ukraine, were being implemented.

"It would be irresponsible to not have a face-to-face encounter and to not directly address with President Putin our positions and concerns on [Ukraine and Syria]," he said.

The way top Kremlin adviser Yuri Ushakov saw it, however, that characterization was flat-out wrong: It was the White House that, in fact, requested the meeting.

"I want to point out right away that White House Press Secretary Earnest's announcement that the Russian president supposedly sought out this meeting -- and repeatedly asked about arranging it -- is not accurate," Ushakov was quoted by Russian news agencies as saying. "We don't turn down invitations."

Casting a further pall over the upcoming meeting were reports that the United States was refusing to negotiate with Russia over a draft statement that Moscow had hoped the UN Security Council would approve to bolster its position on Syria.

The Associated Press reported that the Russian draft urged countries to fight extremist groups "in coordination with the governments of the affected states." That language can be seen as a reference to Syria's government, which Washington and other Western governments have said must go.

"We have concerns that a council presidential statement could be perceived as endorsing an approach that could set back efforts to reach a negotiated political transition in Syria," Sheba Crocker, the assistant U.S. secretary of state for international organization affairs, told reporters on September 24.

The draft, she said, was at "significant variance with the ongoing efforts of a coalition of more than 60 countries, including all of Syria's neighbors to counter" Islamic State (IS) militants.

Russia has sent a sizable contingent of military weaponry and personnel to Syria in recent weeks, including advanced fighter aircraft and antiaircraft missiles. The deployment, Russia's largest outside the Soviet Union in decades, has alarmed Washington, which suspects the Russian forces are there not only to fight IS but also to bolster the forces of Syrian President Bashar al-Assad.

In an interview with CBS News to be broadcast on the eve of the Obama-Putin meeting, the Russian president reiterated Moscow's position that support for the Assad government was key to defeating Islamic radicals.

"And it's my deep belief that any actions to the contrary -- in order to destroy the legitimate government -- will create a situation which you can witness now in the other countries of the region or in other regions, for instance in Libya, where all the state institutions are disintegrated," Putin said, according to a transcript released by CBS.

"We see a similar situation in Iraq," he said.

"And there is no other solution to the Syrian crisis than strengthening the effective government structures and rendering them help in fighting terrorism, but at the same time urging them to engage in positive dialogue with the rational opposition and conduct reform," Putin said.